1) Field of the Disclosure
The disclosure relates generally to aircraft air conditioning systems and methods, and more particularly, to aircraft air conditioning systems and methods for extracting energy from an aircraft engine in a bleed air based aircraft air conditioning system.
2) Description of Related Art
Known air conditioning systems used in transport vehicles, such as commercial aircraft, typically use an air based thermodynamic cycle to provide cool, pressurized air to various interior compartments of the aircraft, such as the passenger cabin, cargo compartments, and other interior compartments. Air from the compressor stages of the main aircraft engines, typically referred to as “bleed air”, may be bled by a bleed air system from two or more of such aircraft's gas turbine engines to supply pneumatic power to various aircraft and engine systems. For example, bleed air may be used to supply pneumatic power to the aircraft air conditioning system, to an aircraft anti-ice system, to an aircraft hydraulic system, or to other aircraft systems or components.
Bleed air may typically be output at a high temperature and a high pressure from the bleed air system of the aircraft engine. Such bleed air may then be cooled and conditioned through air conditioning packs of the aircraft air conditioning system. Once the bleed air is conditioned in the air conditioning packs, it may then be distributed into the aircraft interior for aircraft interior temperature control, ventilation, and pressurization. The conditioned air within the aircraft interior may then be discharged to the outside ambient environment through various overboard valves, overflow valves and cabin leaks.
However, in known bleed based aircraft air conditioning systems, the pneumatic energy or power extracted from the bleed air provided by the bleed air system of the aircraft engine to the aircraft air conditioning system may be decoupled and not aligned with the power or energy needed by the aircraft air conditioning system to meet its flow and cooling demands. The aircraft engine may provide more power than is required by the aircraft air conditioning system power requirements. Such excess power may result in inefficiency and wasted energy. Because the aircraft air conditioning system is typically the largest energy user on the aircraft, other than the propulsion of the aircraft itself, such wasted energy may represent a significant fuel burn impact to the aircraft.
Moreover, in known bleed based aircraft air conditioning systems, the air conditioning (AC) pack of such known aircraft air conditioning systems may require increased pack ram air usage in order to adequately cool the bleed air going into the AC pack. Increased pack ram air usage, and in turn, increased ram air flow, may result in increased ram air drag to the aircraft.
Accordingly, an improved aircraft system and method for extracting energy from an aircraft engine is needed to align the pneumatic power or energy extracted from bleed air provided by the aircraft engines with the power or energy demands of the aircraft air conditioning system, thereby reducing or minimizing wasted energy by the aircraft air conditioning system, and for providing ram air drag savings.